acl before version 2.4.0 contains a symlink traversal vulnerability in the libacl pathname-based functions aclgetfile(), aclsetfile(), aclextendedfile(), and acldeletedef_file() that allows local attackers to escalate privileges by replacing any pathname component with a symbolic link. Attackers who control any component of a pathname processed by a privileged caller can redirect ACL read or write operations to arbitrary files or directories, enabling unauthorized manipulation of access control lists and local privilege escalation.